"Prince Ephraim, you cannot understand. I know the path I'm given is foolish. Yet I am a knight, and I have no other."
- Selena from Fire Emblem: Sacred Stones
I actually don't have a favorite Fire Emblem villain if one were to really ask me but if I had to mention a really dynamic understated character that truly captured my attention, it would have to be Valter from Sacred Stones. The downside being that you see him throughout the story prodding, meddling and being a true presence within the narrative, only to disappear rather suddenly.
Valter, famously known as the 'Moonstone' is the third strongest general of Grado's Imperial Army. He's cunning, sadistic and downright ruthless when it comes to killing innocent civilians. A skilled Wyvern Knight, Valter lusts after Eirika and one of his main reasons for fighting being that he wishes to capture her and make her his puppet bride. He's a disgusting character, you love to hate no matter which route you take.
An interesting thing about him being that he sheds light on other recruitable characters through having previous history with them; - mainly Dussel and Cormag as they knew him before as a decent man, until one fight where he lost a battle and gained a new lance in the process that happened to be cursed (though it truly only amplifies already inherent personalities).
One of my favorite things in Sacred Stones was that even without supports, many of the roster were able to still carry weight in their stories despite not being the lords of the game, themselves. The most heartbreaking scenes for myself in Sacred Stones still to this day, was Valter killing Glen to use and manipulate his younger brother Cormag into trying to kill Eirika. Cormag, learning that Eirika hadn't murdered his brother, went into a rage. Not caring what Eirika's company fought for, he thought only of revenge against the man who had killed his only brother.
There is complete satisfaction through playing the levels with Cormag in his quest of finding out the truth and letting him get his revenge by choosing him as the unit to kill Valter, once and for all. Being able to tune into multiple battle conversations that don't just include the main characters is always a plus in fleshing out a good Fire Emblem roster.
Other examples of battle conversations that I enjoyed in Sacred Stones was Selena's talk with Dussels; and Caellach's dialogue with Joshua.
Mary Ann is your not so average lady from the faraway land of Canadia, as dignified royalty of the North she serves to protect her subjects in both kindness and elegance. For those who wrong her, she wields her hockey stick as her sword and her punches like jackhammers.